Trialkyl phenyl phosphates from purified petroleum alkyl phenols



A Patented June 21, 1949 2.413.012 I rnmrm rm rnosrmrras mom PURIFIED rsraomrmr ALKYL PHENOLS Royal L. Shuman, Newark, N. 1., assimor to Gelanese Corporation of America, a corporation of Delaware No Drawing. O ginal application March 4, 1944, Serial No.'525,l03. Divided and this application December 12, 1946, Serial N0. 715,625

' have a boiling range of 180 alkyl"-phenols which .2 Claims. -(Cl. 26MB!) 1 This invention relates to the-treatment of crude phenolic compounds, and relates more particularly to. the stabilization and purification or alkyl phenols (cresylic acids) extractedfrom petroleum naphtha made by the commercial cracking of crude petroleum. l

This application isa division of my application issued as Patent No. 2,446,250, wherein is claimed the process for the stabilization and purification of alkyl phenols obtained from petroleum.

Le alkyl phenols extracted from petroleum C. to 290 C. or higher and are of the monohydric type. In the process of refining petroleum, four or'flve' fractionsare collated during the distillation and these are commercially available under difl'erent grade designations; The fractions distilling between 200 and 225 C. and between 220 and 250 C. are the ones withwhich the present invention is particularly concerned, since able for the preparation of phosphoric acid esters,

1 excellent plasticizers for cellulose derivatives, re-

sins and other synthetic'compounds. When com merciaily available alkyl phenols extracted from petroleum are reacted with phosphorus halides, such as phosphorus 'oxychloride, to synthesize phosphoric acid esters, such alkyl phenols decompose and discolor, and tarry substances are termed. Moreover, the phosphoric acid esters formed are highly colored and unstable and are not suitable for use in many products. The coloration and instability of the phosphoric acid esters are due to the presence in the alkyl phenols of many phenols which are unstable to phosphorus halides, w well as other undesirable substances such as sulirir-containing impurities, nitrogen bases, neutral oils'y'e'tcw It is, accordingly, an imfportant objectof this invention to provide an improved process for treating alkyl phenols (cresylic acids) extracted from when reacted with phosphorus halides produce stable phosphoric acid esters of good color;

Anotherobject of this invention is theproduc- "tio otf'alkyl phenols (cresylic acidsl'extracted i'riiin petroleum which arefree from phenols unsiable ito phosphorus halides, sulfur-containing iinpiiiities', nitrogen bases,'etc.

Still another object of this invention is the prothey are eminently suit- '8. No. 525,103, filed March 4, 1944, which has I petroleum so as to obtain I examples are given:

du'ction of stabilized and purified alkyl phenols (cresylic acids) obtained from petroleum which have the property of retaining their .color after exposure'to the air for twenty-four hours at room temperature, and oi. reacting with phosphorus 'oxychloride to produce without appreciable reaction discoloration phosphoric acid esters.

A further object to this invention is the preparation of phosphoric acid esters such as trialkyl phenyl phosphates by reacting stabilized and purified alkyl phenols with phosphorus halides, such as phosphorus oxychloride, which phosphoric acid esters have improved electrical resistance, higher viscosities, lower toxicity, and lower density than phosphoric acid esters made from coal tar alkyl phenols.

In accordance with the process of my invention; I treat petroleum .alkyl phenols having a boiling range between 200 and 225 C. and between 220 and 250 C., from which water has been,

from 350 to 400mm. mercury absolute. Any I water produced'during the treatment, as well as any volatile products, are distilled over and-dis: carded. to mm. mercury absolute or less and the heating is continued and the charge is distilled as rapidly as possible. The temperature during distlllation should preferably not exceed 160 C. The

amount of stabilized and purified alkyl phenols recovered from the charge is between and thereof, whichalkyl phenols are highly satisfactory for use in making phosphoric acid esters.

The aluminum chloride employed in accordance withthe present invention is preferably anhydrous and the amounts employed are from 1% to 10% and preferably from of the alkyl phenols being treated.

For the purpose of further describing the invention and not as a limitation, the following Example I (amixture oi cresylic acids) having a boiling The pressure in the still is then reduced j, I

1 to 3%, based on the weight .3 range of 200 to *and a specific gravity of aluminum chloride added. the still is reduced fo250 mm. mercury and heat is applied. The temperature is gradually increased to 140 C. or more in a period of 2 to 8 hours and the pressure is gradually increased to 380 mm. mercury absolute. Any water produced during the treatment. as well as other volatile products. distill oil and are discarded The pressure is then reduced to 50 mm. mercury absolute, or less, heating is continued and the charge is distilled as rapidly as possible. The temperature during the distillation should not exceed 160 C. 85 to 90% of the charge satisfactory for use in making phosphoric acid esters is recovered.

The distillate is water white with a specific gravity of 1.028 at 20 C., a boiling range of 199 to 220 C., and will not discolor when mixed width phosphorus oxychloride and heated.

Example H 5000 parts by weight of petroleum alkyl phenols (a mixture of cresylic acids) having a boiling range of 220 to 245 C. and a specific gravity of 1.008 at 20 C. are charged into a still such as described in Example I. After removing any water present, 150 parts by weight of anhydrous aluminum chloride are added. The pressure in the still is reduced to 300 mm. mercury absolute and heat is applied. The temperature is increased to 150 C. over a period of 3 to 4 hours and the to con mm. mercury absolute. llny water produced during the treatment or other volatile products are distilled oil and discarded. The pressure is then reduced to 50 mm. mercury absolute, or less, heating is continued and the charge is distilled as rapidly as possible. The temperature during the distillation should not exceed 160' C. 80 to 85% or the charge is recoyered and is satisfactory for use in making phosphoric acid esters.

The distillate is light amber to water white in color with a specific gravity of 1.006 at 20 C., a boiling range of 223 C. to 241 C. and will not discolor when mixed with phosphorus oxychloride and heated.

The alkyl phenols (cresylic acids) made in accordance with the present invention are quite superior to those heretofore obtained from petroleum. For example, allryl' phenols heretofore obtained from petroleum even though they are freshly distilled and of with will darken considerably when exposed to air for 24 hours at room temperature, an indication that they are unsuitable for synthesizing phosphoric acid esters. However, the alkyl phenols made in accordance with the present invention remain practically unchanged after exposure to the air for 24 hours at room temperature, i. e. they do not discolor. Moreover, the alkyl phenols heretofore obtained from petroleum discolor appreciably when three mols thereof are heated to 100 C. with one mol of phosphorus oxychloride,- as in the preparation of phosphoric acid esters, whereas the alkyl phenols made in accordance with the present process show little or no discoloration when reacted in the same manner with phosphorus oxychloride.

The alkyl phenols extracted from petroleum after the treatment described in the foregoing.

pared from coal light amber color to begin may be reacted with phosphorus halides, particulariv phosphorus oxychloride, in the same manner as phenols obtained from coal tar are reacted to produce phosphoric acid esters such as triphenyl phosphate, tricres'yl phosphate. etc. subsequent refining of the phosphoric acid esters by vacuum distillation, washing with dilute alkalies, and treatment with strong oxidizing agents such as potassium permanganate is also the same as used for the phosphoric acid esters made from coal tar phenols. The phosphoric acid esters stabilized and purified alkyl thetic products.

The alkyl phenols (cresylic' acids) made in accordance with the present invention yield phosphoric acid when reacted with phosphorus oxychloride, as compared with the phosphoric acid esters pretar phenols having about substantially similar distillation ranges. Thus. they produce phophoric acid esters of improved elecesters of improved characteristics trical qualities, as can be seen from the following comparisons:

Power Resistivity Phosphoric Acid Ester made horn- Factor Ohmscms.

00 cycles X 10 1 Coal tar alkyl phenols with a boiling .966 1,050

point range of $0 to 210 C. and a gravi of L031. 2 Alkyl phenols obtained from. petro- .795 2,750 umandbangaboilingpot range of M to 210 0. (same as l). 3 slwkryl gionols refined in accordance .65 6,500

th sample I above and having a boiling point range of no to 221 C. 4 A131 yillienols ed in accordance .21 21, 200

th sample 11 above and having a boiling point range of 2m to 240. 5 Coal tar alkyiorhenols with a boiling 1.00 127 point range 216 to 226 C. 7

Moreover, the alkyl phenols (cresylic acids) of the present invention yield phosphoric acid esters showing less toxicity than the phosphoric acid esters prepared from alml phenols (cresylic acids) of approximately the same boiling point range. Thus, for example, the phosphoric acid ester prepared from the allryl phenols refined as in Example 1 above has been fed to chickens with the following results:

A single dose of at 20 C. of the phosphoric acid esters prepared from the alkyl phenols produced in accordance with Example I is about 800 centipoises as com pared with the viscosity of about centipoises for the phosphoric acid esters made from the coal tar allwl phenols. This is a very important char acteristic since phosphoric acid esters of higher viscosities are desirable when they are to be used in lubricating oils, and as air filtering mediums as a well as in making plastic compositions. They 8 purified by reacting the alkyl phenols free from water with anhydrous aluminum chloride at an elevated temperature and subatmospheric pres-k sure, and then distilling the reaction mixture to obtain the alkyl phenols as distillates, said trielkyl phenyl phosphates being characterized by Specific Ihosphorio Acid Esters made hom- Gravity 1 Coal taraikyl phenols with a boiling point range ol200to2l0 O. and awciiic gravity ol1.03l..- 1.170 Alkyl phenols refined accordance with Example I above and having a boiling point range of 200 to 2%" O 1. 155 8 Alkyl phenols refined in accordance with E1:-

ample IIabove and havinga boiling point range oimtoZiiPC 1.112

The plastic compositions made with the phosphoric acid esters prepared from the alkyl phenols of the present invention will tolerate or hold more of such phosphoric acid esters than the phosphoric acid esters prepared from coal tar alkyl phenols. For example,- using second R. S; pyroxylin, it 100 parts of phosphoric acid ester made from coal tar alkyl phenols are employed to obtain a certain degree of plasticity or softness, there can be used from 150, to 200 parts of the phosphoric, acid ester of the present invention before reaching the same degree of tackiness or softness. Moreover, in paper coating this loading up of the formula with plasticizer without running into excessive tackiness is a highly desirable property inasmuch as the paper tends to absorb excess plasticizer.

It is to be understood that the foregoing detailed description is given merely by way of iilustration and that many variations may be made therein without departing from the spirit of my invention. 7

Having described my invention. what I desire to secure by Letters Patent is:

. 1. Trialkyl phenyl phosphates prepared by reacting with phosphorus oxychloride alkyl phenols obtained from petroleum, and stabilized and cosities,

having improved electrical resistance, higher vislower toxicity and lower density than phosphoric acid esters made from coal tar alkyl phenols.

2. Trialkyl phenyl phosphates prepared by reacting with phosphorus oxychloride alkyl phenols obtained from petroleum, and stabilized and purified by treating a mixture 01' such alkyl phenols free from water with 1 to 3%. based on the weight of the alkyl phenols, of anhydrous aluminum chloride by heating said mixture at a subatmospheric pressure of about 250 millimeters of mercury absolute and continuing the heating for from 2 to 4 hours while gradually increasing the temperature to at least C. and the pressure to at least 350 millimeters of mercury absolute, then reducing the pressure to about 50 millimeters of mercury absolute and continuing the heating at a temperature at most C. whereby stabilized and purified alkyl phenols are distilled over, said trialkyl phenyl phosphates being characterized by having improved electrical resistance, higher viscosities, lower toxicity and lower density than phosphoric acid esters made from coal tar alkyl phenols.

ROYAL L. SHUMAN.

nnrinanncss crrsn The toll referenlces are of record in the file of this patent:

UNITED STATES PATENTS 

